The invention concerns a method for spectrometric investigation of a plurality of samples which are dissolved in a solvent, comprising the following steps:                (a) guiding a first solvent with a sample through an SPE cartridge for concentrating the sample in the cartridge;        (b) positioning the cartridge in a carrier for a plurality of cartridges;        (c) repeating steps (a) and (b) for a desired number of samples;        (d) drying the concentrated samples through evaporation or vaporization of the residual first solvent;        (e) dissolving each sample in a second solvent, transferring the dissolved samples from the cartridges to a spectrometer and acquiring a spectrum of each sample.        
A method of this type is disclosed in U.S. Pat. No. 6,614,228.
SPE (solid phase extraction) uses small collecting cartridges (SPE cartridges) for collecting and concentrating previously separated mixtures. These have a similar function to a chromatographic separating column on which the sample is retained and eluated from an appropriate composition of solvents.
U.S. Pat. No. 6,614,228 describes a robot device which provides a plurality of SPE cartridges in a carrier. The robot has two clamping devices for inserting each SPE cartridge into the flow path of the first solvent and sealing it to a back pressure of up to 300 bars. The computer-controlled device permits transfer and maintenance of the desired fraction to and in the SPE cartridge through precise switching of interconnected valves. This process can be repeated several times to concentrate the sample.
The cartridge must be completely dried before transfer of the collected substance to a spectrometer. This is achieved by nitrogen flow through the clamped SPE cartridge. The protonized first solvents are evaporated through drying. In a final step, the collected sample is released from the SPE cartridge using second, deuterized organic solvents, and directly inserted into the spectrometer using a flow probe head or into a spectrometer tube.
Drying takes a long time and can only be accomplished for one cartridge at a time. It generally takes about 20 to 35 minutes to completely dry one cartridge. To prevent reaction of the sample at higher temperatures, precaution is required when heating the nitrogen.
U.S. Pat. No. 5,260,028 discloses a fully automatic solid phase extractor (SPE) and a method for operation thereof with which all samples are dried together to facilitate a faster drying of the samples.
U.S. Pat. No. 5,612,002 discloses a partially automatic device for SPE. Vacuum is utilized to simultaneously draw solvent and inert gas through a plurality of SPE cartridges. Moreover, an individual pressure compensation for each SPE unit is described having an over pressure build-up in each reactor tube which can escape via an open capillary. However, as a consequence thereof, only a fraction of the gas is actually used to dry the samples.
US 2004/0013 572 A1 describes a device for fully automatic solid phase extraction with which a plurality of sample vessels are sealed using a plurality of flat, radial seals.
In contrast thereto, it is the underlying purpose of the present invention to propose a method for spectroscopic investigation of a plurality samples with which the drying process is considerably accelerated and rendered more effective using simple technical means.